CN214794871U - Triaxial MEMS capacitive acceleration sensor - Google Patents
Triaxial MEMS capacitive acceleration sensor Download PDFInfo
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- CN214794871U CN214794871U CN202121144983.8U CN202121144983U CN214794871U CN 214794871 U CN214794871 U CN 214794871U CN 202121144983 U CN202121144983 U CN 202121144983U CN 214794871 U CN214794871 U CN 214794871U
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Abstract
The utility model discloses a triaxial MEMS capacitanc acceleration sensor belongs to micro-electromechanical system technical field. The device comprises an upper layer structure for detecting acceleration in an x direction, a middle layer structure for detecting acceleration in a z direction and a lower layer structure for detecting acceleration in a y direction; the upper layer structure and the lower layer structure form a comb-tooth-shaped multiplication capacitance acceleration sensor respectively consisting of a moving electrode and a fixed electrode; the middle layer structure forms a sandwich type differential capacitance acceleration transducer, which comprises an upper and a lower grade plates and a mass block. The utility model has the advantages of electric capacity is just to area big, the range is big, sensitivity is high, the reliability is high, the integrated level is high, with low costs, the noise is low, stable performance.
Description
Technical Field
The utility model relates to micro-electromechanical system technical field, in particular to triaxial MEMS capacitive acceleration sensor.
Background
An MEMS (Micro-Electro-Mechanical System) acceleration sensor is an important inertial device, which can convert a physical signal, i.e., external acceleration, into an electrical signal convenient for measurement, and is widely used in the fields of aviation, aerospace, automobiles, and the like. According to the detection principle, the micro-electromechanical acceleration sensor can be divided into a piezoresistive type, a piezoelectric type, a capacitive type and the like.
A capacitive acceleration sensor is a sensor that converts a measured acceleration signal into a change in the capacitance of a capacitor. The way to achieve this function is usually both of the variable gap type and the variable area type. The movable mass block of the sensor forms a movable electrode of a variable capacitor, when the mass block is subjected to acceleration to generate displacement, the gap or the facing area of a parallel plate capacitor formed by the movable electrode and a fixed electrode is changed, so that the capacitance of the parallel plate capacitor is changed, and the change is detected by a peripheral circuit so as to calculate the acceleration.
In the patent with application number CN201811616953.5, the accelerometer adopts full carborundum material, comprises lower part carborundum stratum basale layer, intermediate junction layer and upper portion carborundum structure frame, and the inside four roof beam quality island structures of five groups array that are equipped with central symmetry of upper portion carborundum structure frame utilizes the pressure drag strip on the roof beam to carry out the vibration perception, and then obtains the acceleration of triaxial direction.
The structure improves the capability of resisting high temperature and severe environment, but has the following problems: the deformation quantity generated by the sensitive piezoresistive strips is limited, and the sensitivity of the sensor is low; the thermomechanical noise generated by the mechanical structure and the piezoresistance is large, and the signal-to-noise ratio of the sensor is low; the piezoresistive material is greatly influenced by temperature, so that the temperature drift of the sensor is caused; the adoption of unconventional materials of silicon carbide brings certain difficulty to the manufacture of the sensor.
In patent application No. CN201921626254.9, a three-axis MEMS capacitive acceleration sensor is proposed. The device comprises a plane detection layer, a comb-tooth-type micro accelerometer, a pendulum-type micro accelerometer, a substrate layer and a vertical detection layer, wherein the comb-tooth-type micro accelerometer is arranged on the plane detection layer and is distributed orthogonally, the acceleration in the horizontal plane is sensed, the pendulum-type micro accelerometer is arranged on the off-plane monitoring layer, the acceleration in the vertical direction is sensed, the substrate layer is arranged between the plane detection layer and the off-plane detection layer, and the substrate layer is arranged on the lower portion of the off-plane detection layer.
This structure can achieve high sensitivity, but has the following problems: the sensor sensing acceleration range is small; the pendulum accelerometer has poor stability and reliability, and the horizontal acceleration sensing capability of the sensor is reduced; the utilization rate of the effective area of the sensor by the two orthogonal comb-tooth type accelerometers in the plane is low.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model provides a triaxial MEMS capacitive acceleration sensor. The sensor has the advantages of large capacitance dead-against area, large measuring range, high sensitivity, high reliability, high integration level, low cost, low noise, stable performance and the like.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
a triaxial MEMS capacitive acceleration sensor comprises an upper layer structure for detecting acceleration in an x direction, a middle layer structure for detecting acceleration in a z direction and a lower layer structure for detecting acceleration in a y direction;
the middle layer structure comprises an upper plate, a fixed frame and a lower plate which are sequentially stacked; a mass block is arranged in the fixed frame and is fixed at the center of the fixed frame through a cantilever group; the lower surface of the upper plate and the upper surface of the lower plate are both provided with a limiting convex frame and an anti-collision convex point for restricting the motion of the mass block; gaps are arranged between the upper-stage plate and the mass block and between the mass block and the lower-stage plate;
the upper layer structure is positioned on the upper surface of the upper-level plate and comprises n x-direction moving electrodes and n +1 x-direction fixed electrodes which are arranged at intervals, wherein n is more than or equal to 1; the x-direction fixed electrode is fixedly connected with the upper-level board, and the x-direction moving electrode is connected with the upper-level board through a flexible structure; the comb teeth are arranged on the adjacent sides of the x-direction moving electrode and the x-direction fixed electrode, and the x-direction moving electrode and the x-direction fixed electrode are arranged in a staggered mode and provided with moving gaps at equal intervals;
the lower layer structure is positioned on the lower surface of the lower-level plate and comprises n y-direction moving electrodes and n +1 y-direction fixed electrodes which are arranged at intervals; the y-direction fixed electrode is fixedly connected with the lower-level plate, and the y-direction moving electrode is connected with the lower-level plate through a flexible structure; comb teeth are arranged on the adjacent sides of the y-direction fixed electrode and the y-direction moving electrode, and the comb teeth of the y-direction moving electrode and the comb teeth of the y-direction fixed electrode are arranged in a staggered mode and provided with moving gaps at equal intervals; the x-direction moving electrode and the y-direction moving electrode are perpendicular to each other.
Furthermore, the upper surface and the lower surface of the mass block are both square; the cantilever group comprises an upper group of cantilevers and a lower group of cantilevers which correspond to the upper surface and the lower surface of the square respectively, and each group of cantilevers comprises four cantilevers which are rotationally symmetrical; the cantilever is of a Z-shaped structure, and two ends of the cantilever are respectively connected with the peripheral frame and the square edge end point.
Furthermore, the cantilevers which are opposite to each other in the upper and lower positions are connected with the opposite side end points of the corresponding square edges.
Furthermore, the upper surface of the upper plate and the lower surface of the lower plate are both covered with insulating layers, anchor points are arranged on the upper surface of the upper plate and the lower surface of the lower plate, and the x-direction moving electrode and the y-direction moving electrode are connected to the corresponding anchor points through flexible structures.
Furthermore, the outer surfaces of the anti-collision convex points and the limiting convex frame are respectively covered with an insulating layer.
Further, n is 2.
A manufacturing method of a triaxial MEMS capacitive acceleration sensor is used for manufacturing the acceleration sensor and comprises the following manufacturing steps:
first, the fabrication of the upper layer structure and the upper layer board,
selecting a low-resistance SOI silicon wafer with polished double surfaces and carrying out primary oxidation on the low-resistance SOI silicon wafer;
etching an x-direction fixed electrode, an x-direction moving electrode, a flexible structure and a corresponding anchor point on the front surface of the oxidized low-resistance SOI silicon chip; etching the back surface of the oxidized low-resistance SOI silicon wafer to form a limiting convex frame;
thirdly, oxidizing the low-resistance SOI silicon wafer again;
releasing the x-direction moving electrode on the front surface of the low-resistance SOI silicon chip; reserving the anti-collision salient points and the oxide layer on the limiting convex frame on the back surface of the low-resistance SOI silicon chip, and removing the oxide layer at other positions in the limiting convex frame area; thereby obtaining an upper layer structure and an upper layer plate;
secondly, manufacturing the mass block and the fixing frame,
carrying out front wet deep etching on two low-resistance silicon wafers with polished double surfaces to obtain two groups of low-resistance silicon wafers with cavities under arms;
step two, making the underarm cavities of the two groups of low-resistance silicon chips opposite to each other, and carrying out silicon-silicon bonding;
etching an upper group of cantilevers and a lower group of cantilevers on the upper surface and the lower surface of the bonded low-resistance silicon wafer; thereby obtaining a mass block and a fixed frame;
thirdly, manufacturing a lower layer structure and a lower layer plate,
selecting a low-resistance SOI silicon wafer with polished double surfaces and carrying out primary oxidation on the low-resistance SOI silicon wafer;
etching a y-direction fixed electrode, a y-direction moving electrode, a flexible structure and a corresponding anchor point on the front surface of the oxidized low-resistance SOI silicon wafer; etching the back surface of the oxidized low-resistance SOI silicon wafer to form a limiting convex frame;
thirdly, oxidizing the low-resistance SOI silicon wafer again;
releasing a y-direction moving electrode on the front surface of the low-resistance SOI silicon chip; reserving the anti-collision salient points and the oxide layer on the limiting convex frame on the back surface of the low-resistance SOI silicon chip, and removing the oxide layer at other positions in the limiting convex frame area; thereby obtaining a lower structure and a lower plate;
and after the steps are finished, connecting the obtained parts in a silicon-silicon bonding mode according to the corresponding relation.
The utility model adopts the beneficial effect that above-mentioned technical scheme produced lies in:
1. the utility model discloses a three-axis capacitance type acceleration sensor has effectively improved the utilization ratio of vertical direction silicon chip, has guaranteed sensor range and sensitivity when improving the integrated level, reducing the volume.
2. The utility model discloses a triaxial capacitive acceleration sensor, it is big to receive the little and measuring range of temperature influence, the stable performance.
3. The utility model discloses an x, y direction broach type multiplication electric capacity acceleration sensor utilize sharing fixed electrode to effectively increase the sensor capacitance variation, improve the sensitivity of acceleration.
4. The utility model discloses a Z direction sandwich type differential capacitance acceleration sensor utilizes the effective increase quality piece movable range of Z type structure, improves the electric capacity variable quantity and then improves the sensitivity of acceleration.
5. The utility model discloses each layer structure adopts the silicon-silicon bonding, has effectively guaranteed the key and the intensity of sensor, has improved the reliability of sensor.
6. The utility model discloses each layer adopts the low resistance silicon material, and easily the lead wire has effectively reduced the cost of manufacture, has reduced the degree of difficulty of each layer electrode preparation simultaneously.
7. The utility model discloses set up spacing protruding frame and anticollision bump, can prevent in bonding, scribing and the use, the sensor that causes destroys or inefficacy.
Drawings
Fig. 1 is a schematic view of the overall structure of the embodiment of the present invention.
Fig. 2 is a schematic view of a portion of the structure of fig. 1.
Fig. 3 is a schematic view of the structure of the mass block and the cantilever in fig. 2.
Fig. 4 is a schematic diagram of the upper layer structure of fig. 1.
Fig. 5 is a schematic view of the lower surface of the upper plate of fig. 1.
Fig. 6 is a schematic view of the lower layer structure of fig. 1.
Fig. 7 is a schematic top view of the lower plate of fig. 1.
In the figure: 31. the structure comprises an upper layer structure, a 32 middle layer structure, a 33 lower layer structure, a 41, 45, 48, an x-directional fixed electrode, a 42, x-directional flexible structure, a 43, x-directional anchor point, a 44, an upper layer board lead area, a 46, an insulating layer, a 47, an upper layer board, a 51, an upper layer board insulating layer, a 52, a limit convex frame, a 53, a bump, a 61, 63, a cantilever, a 62, z-directional lead area, a 64, a mass block, a 65, a fixing frame, a 71, a lower layer board insulating layer, a 72, a limit convex frame, a 73, a bump, an 81, 85, 88, a y-directional fixed electrode, a 82, y-directional flexible structure, a 83, a y-directional anchor point, a 84, a lower layer board lead area, a 86, an insulating area, a 87 and a lower layer board.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1 to 7, the present embodiment includes an upper layer structure 31 composed of an x-direction fixed electrode, an x-direction moving electrode, an x-direction anchor point, an x-direction flexible structure and a lead region of an upper layer board, a middle layer structure 32 composed of an upper layer board, a lower layer board, a mass block, a cantilever, and the like, and a lower layer structure 33 composed of a y-direction fixed electrode, a y-direction moving electrode, a y-direction anchor point, a y-direction flexible structure and a lead region of a lower layer board.
Wherein the x-directional fixed electrode 41, the x-directional moving electrode and the x-directional anchor point 43 are positioned on the top of the upper plate, and the x-directional moving electrode and the x-directional anchor point are connected through the x-directional flexible structure 42.
The upper surface of the upper-level plate is provided with an insulating layer, and the lower surface of the lower-level plate is provided with an insulating layer; the limit convex frame of the upper plate is consistent with the square inside the fixed frame, the anti-collision salient points of the upper plate are over against the position of the mass block, and the lead area 44 of the upper plate is positioned at the edge position of the upper plate.
The inner end of each cantilever 61 in the upper group of cantilevers is connected with the upper surface of the mass block 64, and the outer end of each cantilever in the upper group of cantilevers is connected with the upper surface of the fixed frame 65; the inner end of each cantilever in the lower group of cantilevers is connected with the lower surface of the mass block, and the outer end of each cantilever in the lower group of cantilevers is connected with the lower surface of the fixed frame; the upper group of cantilevers and the lower group of cantilevers are rotationally symmetrical about the center of the mass block, a z-direction lead area 62 is arranged at the edge position of the fixed frame, and the z-direction lead area and the upper-level board lead area are arranged on the same side but the projection positions are not overlapped.
The y-direction fixed electrode 81, the y-direction moving electrode and the y-direction anchor point 83 are all positioned at the bottom of the lower-level plate, and the y-direction moving electrode is connected with the y-direction anchor point through a flexible structure; the lower surface of the lower plate is provided with an insulating layer, the anti-collision salient points of the lower plate are positioned on the upper surface of the lower plate, the squares in the limiting convex frame fixing frame of the lower plate are consistent, the anti-collision salient points of the lower plate are opposite to the position of the mass block, the lead area of the lower plate is positioned at the edge position of the lower plate, and the lead area 84 of the lower plate 87, the lead area of the upper plate and the lead area of the lower plate in the z direction are positioned at the same side but the projection positions are not overlapped.
The sensor adopts an x-direction fixed electrode and an x-direction moving electrode to form a comb-tooth-shaped multiplication capacitance acceleration sensor for sensing acceleration in the x direction; a y-direction fixed electrode and a y-direction moving electrode are adopted to form a comb-tooth-shaped multiplication capacitance acceleration sensor for sensing acceleration in the y direction; the sandwich type differential capacitance acceleration sensor for sensing the acceleration in the z direction is formed by an upper plate, an upper group of cantilevers, a lower group of cantilevers, a mass block and a lower plate.
The sensor is composed of an upper layer structure, a middle layer structure and a lower layer structure, and achieves the function of triaxial acceleration sensing, the insulating layer 46 on the upper surface of the upper layer plate 47 provides a silicon oxide isolating layer for the sensor sensing the x direction and the z direction, and the insulating layer 86 on the lower surface of the lower layer plate provides a silicon oxide isolating layer for the sensor sensing the y direction and the z direction.
The upper layer structure and the lower layer structure of the sensor are made of SOI silicon chips, and the middle layer structure is made of two low-resistance silicon chips; the upper layer structure and the middle layer structure are formed by bonding the insulating layer on the lower surface of the upper layer plate and the fixing frame by silicon-silicon bonding, and the lower layer structure and the middle layer structure are formed by bonding the insulating layer on the upper surface of the lower layer plate and the fixing frame by silicon-silicon bonding.
The x-direction moving electrode and the y-direction moving electrode 82 of the sensor provide elasticity for sensing acceleration in the x direction or the y direction through a flexible structure.
The sensor adopts dry etching to obtain an upper group of cantilevers and a lower group of cantilevers which are respectively positioned on the upper side and the lower side of the mass block and are both of elastic movable beam structures, so that elasticity is provided for forced movement of the mass block.
The sensor adopts twice oxidation and etching to form an upper layer structure and a step interval of a lower layer structure, namely a limiting convex frame of an upper plate and a limiting convex frame of a lower plate are formed, a capacitance gap is provided for the sandwich type acceleration differential sensor for sensing the acceleration in the z direction, a warning effect is provided for bonding, scribing and using, damage to the sensor caused by scribing is prevented, failure of the sensor caused by attraction of a mass block and the upper plate and the lower plate due to external force in the bonding and using processes is prevented, meanwhile, anti-collision bumps of the upper plate and the lower plate are formed, failure of the sensor caused by attraction of the mass block and the upper plate and the lower plate during up-and-down movement can be prevented by the arrangement, and reliability of the sandwich type acceleration differential sensor for sensing the acceleration in the z direction is improved.
The sensor is characterized in that an x-direction fixed electrode, an x-direction moving electrode, an x-direction anchor point, an upper-stage plate, an upper group of cantilevers, a lower group of cantilever beams, a mass block, a fixed frame, a y-direction fixed electrode, a y-direction moving electrode, a y-direction anchor point and a lower-stage plate are all low-resistance silicon materials; the insulating layer, the upper board insulating layer 51, the upper board bump 53, the lower board insulating layer 71, the lower board bump 73, and the insulating layer 86 are all silicon oxide.
The working principle of the utility model is as follows:
the acceleration of the triaxial MEMS capacitive acceleration sensor in the x and y directions is sensed as a comb-tooth-type multiplied capacitance acceleration sensor, the comb-tooth-type multiplied capacitance acceleration sensor consists of a moving electrode and a fixed electrode, when the acceleration in the x or y direction is received, the moving electrode moves along the x or y direction, and the capacitance value of a parallel plate capacitor consisting of the moving electrode and the fixed electrode changes; when the acceleration in the Z direction is received, the mass block moves along the Z direction, the capacitance value of a parallel plate capacitor formed by the upper and lower stages changes, and the acceleration value in the Z direction is obtained by using the differential capacitance.
The working principle of acquiring the acceleration value in the x or y direction is as follows:
under the ideal circumstances, the dynamic electrode broach is located fixed electrode broach intermediate position, and under the condition that does not have the acceleration, the dynamic electrode does not take place the motion, and the expression of broach capacitance value is:
in the formula Cs0Is the initial capacitance value of a single comb-tooth type capacitance acceleration sensor, epsilon is the relative dielectric constant, SsThe area of each comb tooth is positive and opposite to the area, d, of a single comb tooth type capacitance acceleration sensors0Is the initial space between the comb teeth.
When the triaxial MEMS capacitive acceleration sensor senses acceleration in the x or y direction, the forced movement of the movable electrode generates displacement xsThe capacitance difference of the single comb-tooth type capacitive acceleration sensor thus obtained is:
then the capacitance value obtained when the acceleration is sensed in the x or y direction is 2 times of the capacitance difference value of the single comb-tooth type capacitance acceleration sensor, and the acceleration value can be calculated as follows:
in the formula msAs the movable electrode mass, ksIs the system elastic stiffness.
The working principle of acquiring the acceleration value in the z direction is as follows:
ideally, the mass block is located at the middle position of the upper and lower polar plates, and the mass block does not move under the condition of no acceleration, and the expressions of the upper and lower capacitance values are as follows:
in the formula C1、C2Respectively the capacitance values of the upper and lower parts, S is the area of mass block facing the upper and lower polar plates, d0The initial distance between the mass block and the upper and lower polar plates.
When the triaxial MEMS capacitive acceleration sensor senses the acceleration in the Z direction, the mass block moves forcedly to generate displacement x, and the obtained capacitance difference value of the sandwich type capacitive acceleration sensor is
Calculating an acceleration value from a capacitance value obtained when the acceleration is sensed in the z direction as:
wherein m is mass of the mass block, and k is elastic rigidity of the system.
The preparation process of the upper layer structure and the upper plate mainly comprises the following steps:
firstly, oxidizing a low-resistance SOI silicon wafer with two polished surfaces for the first time to form an oxide layer on the upper surface and the lower surface of the SOI silicon wafer;
removing an oxide layer on the upper surface of the SOI silicon chip by adopting dry etching to form a front pattern, wherein the pattern is consistent with the edge shapes of the x-direction fixed electrode, the x-direction moving electrode, the x-direction anchor point and the lead area of the upper-level plate;
removing an oxide layer on the lower surface of the SOI silicon wafer by adopting dry etching to form a reverse pattern, wherein the shape of the pattern is consistent with that of a limiting convex frame of a superior plate;
fourthly, carrying out second oxidation on the SOI silicon wafer after the photoetching is finished, wherein the thickness of the oxidation layer at the back pattern position is lower than that of the oxidation layer at the peripheral position;
removing an oxide layer and other redundant oxide layers below the front x-direction moving electrode of the SOI silicon wafer by wet etching, and releasing the edges of the front x-direction moving electrode and the lead area of the upper-level plate;
removing an oxide layer on the back side of the SOI silicon wafer by wet etching to form a limiting convex frame of the upper plate and keep the anti-collision convex points of the upper plate;
and seventhly, obtaining a superior plate lead area on the front surface of the SOI silicon chip by adopting dry etching.
The preparation process of the quality block and the fixed frame in the middle layer structure mainly comprises the following steps:
the method comprises the following steps that firstly, the front side of a low-resistance silicon wafer with two polished sides is deeply etched by adopting wet etching, and a lower arm cavity of an upper group of cantilevers and a lower arm cavity of a lower group of cantilevers are obtained by utilizing an automatic stop etching process;
selecting two low-resistance silicon wafers subjected to deep etching, and carrying out silicon-silicon bonding on the front surfaces of the two low-resistance silicon wafers to complete the lower cavity structure of the double-sided clip arm in the middle layer structure;
removing the redundant part of the silicon wafer by adopting dry etching to form an upper group of cantilevers and a lead area in the z direction on the front side of the bonded silicon wafer;
removing the redundant part of the silicon wafer by adopting dry etching to form a lower group of cantilever beams on the reverse side of the bonded silicon wafer;
the preparation process of the lower layer structure and the lower plate mainly comprises the following steps:
firstly, oxidizing a low-resistance SOI silicon wafer with two polished surfaces for the first time to form an oxide layer on the upper surface and the lower surface of the SOI silicon wafer;
removing an oxide layer on the upper surface of the SOI silicon chip by adopting dry etching to form a front pattern, wherein the pattern is consistent with the edge shapes of the y-direction fixed electrode, the y-direction moving electrode, the y-direction anchor point and the lower-level plate lead area;
removing the oxide layer on the lower surface of the SOI silicon wafer by adopting dry etching to form a reverse pattern, wherein the shape of the pattern is consistent with that of the limiting convex frame of the lower plate;
fourthly, carrying out second oxidation on the SOI silicon wafer after the photoetching is finished, wherein the thickness of the oxidation layer at the back pattern position is lower than that of the oxidation layer at the peripheral position;
removing an oxide layer and other redundant oxide layers below the front y-direction moving electrode of the SOI silicon wafer by wet etching, and releasing the edges of the front y-direction moving electrode and a lower-level plate lead region;
removing a back oxidation layer of the SOI silicon wafer by wet etching to form a lower plate limiting convex frame and keep a lower plate anti-collision convex point;
and seventhly, obtaining a lower-level plate lead area on the front surface of the SOI silicon chip by adopting dry etching.
After the upper layer structure 31, the middle layer structure 32 and the lower layer structure 33 are respectively prepared, the left sides of the upper layer structure 31, the middle layer structure 32 and the lower layer structure 33 are aligned, and the bonding of the three-layer structure of the three-axis MEMS capacitive acceleration sensor is completed by adopting the order from top to bottom of the upper layer structure 31, the middle layer structure 32 and the lower layer structure 33 and using a silicon-silicon bonding method.
The utility model discloses can carry out the acceleration perception to x, y, Z direction, have advantages such as small, the range is big, sensitivity is high, the reliability is high, the integrated level is high, with low costs, the noise is low, stable performance, can carry out quantity control to fixed electrode, movable electrode, the shape cantilever beam of returning according to service environment's demand to obtain different system elastic coefficient and system characteristic frequency.
Claims (6)
1. A triaxial MEMS capacitive acceleration sensor is characterized by comprising an upper layer structure for detecting acceleration in an x direction, a middle layer structure for detecting acceleration in a z direction and a lower layer structure for detecting acceleration in a y direction;
the middle layer structure comprises an upper plate, a fixed frame and a lower plate which are sequentially stacked; a mass block is arranged in the fixed frame and is fixed at the center of the fixed frame through a cantilever group; the lower surface of the upper plate and the upper surface of the lower plate are both provided with a limiting convex frame and an anti-collision convex point for restricting the motion of the mass block; gaps are arranged between the upper-stage plate and the mass block and between the mass block and the lower-stage plate;
the upper layer structure is positioned at the top of the upper-level plate and comprises n x-direction moving electrodes and n +1 x-direction fixed electrodes which are arranged at intervals, wherein n is more than or equal to 1; the x-direction fixed electrode is fixedly connected with the upper-level board, and the x-direction moving electrode is connected with the upper-level board through a flexible structure; the comb teeth are arranged on the adjacent sides of the x-direction moving electrode and the x-direction fixed electrode, and the x-direction moving electrode and the x-direction fixed electrode are arranged in a staggered mode and provided with moving gaps at equal intervals;
the lower layer structure is positioned at the bottom of the lower-level plate and comprises n y-direction moving electrodes and n +1 y-direction fixed electrodes which are arranged at intervals; the y-direction fixed electrode is fixedly connected with the lower-level plate, and the y-direction moving electrode is connected with the lower-level plate through a flexible structure; comb teeth are arranged on the adjacent sides of the y-direction fixed electrode and the y-direction moving electrode, and the comb teeth of the y-direction moving electrode and the comb teeth of the y-direction fixed electrode are arranged in a staggered mode and provided with moving gaps at equal intervals; the x-direction moving electrode and the y-direction moving electrode are perpendicular to each other.
2. The triaxial MEMS capacitive acceleration sensor of claim 1, characterized in that the upper and lower surfaces of the mass are both square; the cantilever group comprises an upper group of cantilevers and a lower group of cantilevers which correspond to the upper surface and the lower surface of the square respectively, and each group of cantilevers comprises four cantilevers which are rotationally symmetrical; the cantilever is of a Z-shaped structure, and two ends of the cantilever are respectively connected with the peripheral frame and the square edge end point.
3. The triaxial MEMS capacitive acceleration sensor of claim 2, wherein the cantilevers facing up and down are connected to opposite side ends of the corresponding square edge.
4. The triaxial MEMS capacitive acceleration sensor of claim 1, wherein the upper surface of the upper plate and the lower surface of the lower plate are covered with an insulating layer, and the upper surface of the upper plate and the lower surface of the lower plate are provided with anchor points, and the x-directional moving electrode and the y-directional moving electrode are connected to the corresponding anchor points through flexible structures.
5. The triaxial MEMS capacitive acceleration sensor according to claim 2, characterized in that the bump bumps and the bump stops are covered with an insulating layer on the outer surface.
6. The triaxial MEMS capacitive acceleration sensor of claim 1, characterized in that said n-2.
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| CN114383762A (en) * | 2022-01-11 | 2022-04-22 | 西安交通大学 | MEMS capacitive micro-force sensor based on multi-comb array and decoupling test method |
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| CN114383762A (en) * | 2022-01-11 | 2022-04-22 | 西安交通大学 | MEMS capacitive micro-force sensor based on multi-comb array and decoupling test method |
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